Silica heat barrier



Dec. 10, 1963 ELECTRONIC CONTROLS AUXILIARY ENG/NE, FUEL M- M. WALLER SILICA HEAT BARRIER Filed Feb. 2, 1959 FUEL MAIN ENG/NE INVENTOR.

MILTON M. WALLER ATTORNEYS United States Patent 3,113,521 SILICA EEAT BAER Milton M. Waller, Plainfield, N..l., assignor to Nuclear Corporation of America, Inc., Denville, NJL, a corporation of Delaware Filed Feb. 2, 1959, Ser. No. 790,735 5 Claims. (Cl. 162-925) This invention relates to arrangements for protection against heat or other radiations.

In a number of important situations, it is desirable to use materials which retain mechanical strength at high temperatures, and which do not transmit heat readily. One particularly important application of this type is in the nose cone of a high speed re-entry vehicle. Because of its high melting point and high temperature rigidity, it has been proposed that fused quartz be employed as a nose cone material. However, because quartz transmits infrared radiations, the warhead and electronic equipment within the nose cone tend to get extremely hot, once the fused quartz nose cone begins to heat up.

Accordingly, a principal object of the present invention is to reduce the heat or infrared transmission properties of fused quartz.

In accordance with the present invention, it has been discovered that this object may be achieved through the addition of gadolinium or one of the other rare earth materials to quartz. More specifically, excellent results have been obtained through the use of fused quartz made with approximately 1 percent of gadolinium oxide and 99 percent silica. The silica may initially be in the form of quartz crystals or quartz sand. It is also contemplated that useful results may be obtained by using from traces of, for example about .01 percent, gadolinum, up to several percent of this material. The other rare earths are also applicable to this problem, as they have generally simliar properties to gadolinium. Particularly for situations in which nuclear radiations may also be present, however, gadolinium is to be preferred in view of its known radiation absorption properties.

Other objects, and various features and advantages of the present invention will become apparent from a consideration of the following detailed description and from a consideration of the single FIGURE of the drawing.

With reference to the drawing, the illustrative embodiment of the invention constitutes a multi-stage rocket 2. This multi-stage rocket is of a conventional design and includes a separate nose cone assembly 4. In accordance with known techniques, following the consumption of the fuel in the main portion of the rocket 2, the nose cone assembly 4 is separated from the main body portion of the rocket 2. The nose cone assembly 4 may include a warhead 6, electronic controls 8 and an auxiliary engine and fuel supply The outer surface of the nose cone is covered with a shell 12 which may, for example, be a gadolinium quartz material of the type described above.

As the nose cone assembly returns to earth, frictional forces between the nose cone and the atmosphere will greatly increase the temperature of the outer surface of the nose cone. Without the rare earth additions in the quartz, the infrared radiations and the heat from the outer surface of the quartz layer would be readily transmitted to the interior of the nose cone. The presence of the 'ice rare earth additions, however, causes an absorption and reradiation of the heat from the outer layer of the nose cone. The remainder of the quartz then constitutes a heat barrier which shields the interior of the nose cone from infrared radiations and from 'high temperatures.

As mentioned above, the composition of the nose cone may be of about .01 to 10 percent, preferably .3 to 2 percent gadolinium oxide, the remainder being quartz, and beneficial results may be obtained by using other of the rare earths in similar percentages. The other metals generally known as rare earths include lanthanum, cerium, praseodymium, neodymium, Samarium, europium, terbium, tdysprosium, holmium, erbium, thulium, ytterbiurn, and lutetium. Scandium and yttrium, atomic numbers Z1 and 39, occur together with the rare earths in nature, and are also Group IIIA elements. These elements are therefore normally included in the group of rare earths, and will be so included for the purpose of the present specification and claims. Of the rare earth materials mentioned above, samarium and europium in addition to gadolinium, have higher thermal neutron cross-sections than any other naturally occurring materials. These elements are therefore particularly suitable for the present purposes, in which the property of inhibiting radiation and subatomic particles is a useful collateral property With respect to the primary function of inhibiting heat transfer through the quartz material.

The material in accordance with the present invention is also suitable for use as an ablating or as a heat insulating material for purposes other than the nose cone of high speed re-entry vehicles. Thus, for example, the material could be used for some types of jet nozzles and for the lining of ovens or low temperature furnaces.

It is to be understood that the above described arran gements are illustrative of the application of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope of the invention. By Way of example but not of limitation, it may be noted that the additional rare earth material may be essentially pure or in the form of compounds such as oxides of the elements.

What is claimed is:

1. A missile comprising a nose cone made of quartz, said quartz containing .01 to 10 percent of gadolinium, and means for mounting electronic equipment in said nose cone.

2. A high speed re-entry vehicle comprising a nose cone made principally of quartz, said quartz containing .01 to 10 percent of gadolinium.

3. In combination, a heat barrier comprising fused quartz, said quartz containing 10 1 to 10 percent of gadoliniurn, means for subjecting a region adjacent one side of said barrier to elevated temperatures and heat sensitive equipment located adjacent said barrier on the other side thereof.

4. In combination, a heat barrier comprising fused quartz, said quartz containing .01 to 10* percent of a material selected from the group consisting of stable rare earth elements and oxides thereof, means for subjectinga region adjacent one side of said barrier to elevated temperat-ures and heat sensitive equipment located adjacent said barrier on the other side thereof.

5. A 'high speed re-entry vehicle comprising a nose cone made principally of quartz, said quartz including 0.3 to 2 percent of material selected from the group consisting of gadolinium and gadolinium oxide. 2,862,131

References Cited in the file of this patent 2,976,806

UNITED STATES PATENTS 5 2,578,325 Sun et a1. Dec. 11, 1951 73 405 2,782,716 Johnston Feb. 26, 1957 297 259 4 Loifler Sept. 3, 1957 Desrivieres Nov. 25, 1958 Winn May 24, 1960 Risk Mar. 28, 1961 FOREIGN PATENTS Germany Sept. 15, 1893 Italy June 8, 1932 

3. IN COMBINATION, A HEAT BARRIER COMPRISING FUSED QUARTZ, SAID QUARTZ CONTAINING .01 TO 10 PERCENT OF GADOLINIUM, MEANS FOR SUBJECTING A REGION ADJACENT ONE SIDE OF SAID BARRIER TO EVELATED TEMPERATURES AND HEAT SENSITIVE 